Skin structure and interior part using the same

ABSTRACT

A skin structure is constituted by laminating a space holding layer  1  and a low lightness layer  2  on a base material  3,  laminating the space holding layer  1  on a base material  4  of low lightness, or laminating a space holding layer  5  of low lightness on the base material  3.  Accordingly, an increase in surface temperature of an interior material caused by direct solar radiation or solar radiation through glass and reflection in a window can be prevented.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an interior material and an interior part for reducing summer heat and providing a comfortably temperatured environment. Specifically, the present invention relates to a skin structure for reducing an increase in temperature of a vehicle interior parked in the blazing sunshine, and for reducing heat radiated therefrom to occupants. The present invention also relates to an interior part using the skin structure.

[0003] 2. Description of the Related Art

[0004] As is generally known, the interior temperature of a vehicle parked in the blazing sunshine becomes very high. In a measured example of a summer environment in Japan, the vehicle's interior temperature reaches nearly 70° C. Particularly, for the temperature of interior material in vehicle, the temperature of the top surface of an instrument panel reaches nearly 100° C. Needless to say, it is unpleasant for occupants to get into the vehicle in such circumstances. Even if ventilation or air-conditioning is activated, the surface temperature of the interior material cannot easily reduce, and heat radiation continues to be released toward occupants for a long period of time. Accordingly, the comfort of the occupants is greatly impaired.

[0005] With regard to such a problem of parking in the blazing sunshine, there have been hitherto proposed a number of methods, for example a method of performing ventilation by use of a solar battery as proposed in Japanese Patent Application Laid-open No. 9-295509 (1997). For the purpose of preventing to heat the interior material, like as Japanese Patent Application Laid-open No. 2001-114149 and Japanese Patent Application Laid-open No. 2001-122044, there has been proposed a method of reflecting near-infrared radiation by allowing a skin of the interior material to contain an infrared reflective pigment. In Japanese Patent Application Laid-open No. 10-109571 (1998), it has been proposed that a laminated material composed of a raw material reflecting sunbeams and a raw material absorbing sunbeams is used as a reflective cover. This cover is used on the top surface of the instrument panel and set with a reflection surface faced up while parking and with absorption surface faced up while driving.

SUMMARY OF THE INVENTION

[0006] however, in the technology like as Japanese Patent Application Laid-open No. 9-295509 (1997), only small part of air inside the vehicle is exchanged with outside air. Therefore, it has been confirmed that the technology barely contributes to the reduction of the above-described unpleasantness. Particularly, this technology had no effect on heat radiation from the interior material. In the technologies of Japanese Patent Application Laid-open No. 2001-114149 and Japanese Patent Application Laid-open No. 2001-122044, since powder of the infrared reflective pigment is mixed with resin, the infrared radiation is diffusely reflected. Accordingly, most of the reflected rays are absorbed by the resin, so that an effect of reflection cannot be substantially obtained when taking a broad view of material. Furthermore, in recent years, as window glass for the automobile, heat insulating type glass absorbing near infrared radiation has become popular. Since the conventional technology has a structure of reflecting only near-infrared radiation, the effect of preventing overheating cannot be anticipated. In technology such as Japanese Patent Application Laid-open No. 10-109571 (1998), the operation of reversing the laminated material upon each occasion of getting into and out of vehicle is troublesome, so that the technology lacks practical use. If the size of a product thereof is determined so as to allow easy handling of the product, only small part of the overheated surface can be covered in the interior. Accordingly, not a great deal of effect can be expected for the vehicle as a whole.

[0007] The present invention has been in consideration of the above problems. The object of the present invention is to suppress an increase in surface temperature of the interior material caused by direct solar radiation or solar radiation through glass. Here, in most of the portions receiving the solar radiation, lightness thereof must be lowered out of consideration that reflection in the window glass would not interfere with the field of vision of the occupant. Since the lowering of lightness allows the interior material to effectively absorb the solar radiation and overheat, the lowering of lightness has an ironic relationship with the prevention of overheating. Another object of the present invention is to solve such a problem permanently by means of the skin fixed to the interior part, not by means of an operation by the occupant as in the case of the reflective cover.

[0008] The conventional art faced the problems as described above because of using a raw material reflecting solar radiation as the method of preventing an increase in surface temperature of the interior material. In the present invention, the conventional concept was renounced, and the application of a transmission principle, which is an entirely new principle, is attempted. Specifically, in the present invention, first, a direct increase in temperature of the surface layer is prevented by allowing solar radiation to be transmitted to a low lightness layer of a bottom layer. The sunbeams are absorbed in the low lightness layer and then generate heat. In this case, if the low lightness layer generating heat allows the heat to easily propagate to the top skin, an indirect increase in temperature is caused. In order to reduce the increase in temperature, the surface of the interior is structured to have a space holding layer for holding space to give a function of heat insulation and retention on the low lightness layer as the heat generation layer.

[0009] The first aspect of the present invention provides a skin structure, comprising: a base material; a low lightness layer laminated on the base material, the low lightness layer showing low lightness to incident light; and a space holding layer laminated on the low lightness layer, the space holding layer forming a space on the low lightness layer.

[0010] The second aspect of the present invention provides a skin structure, comprising: a base material; and a space holding layer laminated on the base material, the space holding layer forming a space on the base material, wherein the base material is set to have low lightness.

[0011] The third aspect of the present invention provides a skin structure, comprising: a base material; and a space holding layer laminated on the base material, the space holding layer forming a space on the base material, wherein the space holding layer is set to have low lightness.

[0012] The fourth aspect of the present invention provides an interior part, comprising: a skin structure comprising a base material; a low lightness layer laminated on the base material, the low lightness layer showing low lightness to incident light; and a space holding layer laminated on the low lightness layer, the space holding layer forming a space on the low lightness layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention will now be described with reference to the accompany drawings wherein;

[0014]FIG. 1 is a schematic cross-sectional view showing a skin structure of a conventional representative instrument panel;

[0015]FIG. 2 is a schematic cross-sectional view showing a representative example of a skin structure according to the present invention;

[0016]FIG. 3 is a schematic cross-sectional view showing an example of the skin structure according to the present invention;

[0017]FIG. 4 is a schematic cross-sectional view showing a skin structure obtained by eliminating the light transmitting layer from the skin structure shown in FIG. 3;

[0018]FIG. 5 is a schematic cross-sectional view showing another example of the skin structure of the present invention;

[0019]FIG. 6 is a schematic cross-sectional view showing a skin structure obtained by eliminating the light transmitting layer from the skin structure shown in FIG. 5;

[0020]FIG. 7 is a schematic cross-sectional view showing another example of the skin structure of the present invention;

[0021]FIG. 8 is a schematic cross-sectional view showing a skin structure obtained by eliminating the light transmitting layer from the skin structure shown in FIG. 7;

[0022]FIG. 9 is a view showing interior parts using the skin structure of the present invention;

[0023]FIG. 10 is a schematic view for explaining the evaluation method of the artificial sunlight test; and

[0024]FIG. 11 is a schematic view for explaining sensory evaluation of the reflection in the window.

DETAILED DESCRIPTION OF THE PREFERED EMBODIMENT

[0025] Hereinafter, description will be made of embodiments of the present invention with reference to the drawings.

[0026] First, detailed description will be made for a mechanism of preventing an increase in temperature according to the present invention with reference to the drawings. FIG. 1 shows a schematic view of a skin structure of a conventional representative instrument panel and a balance of a solar radiation energy. In FIG. 1, the skin structure is composed of a polyvinyl chloride resin skin 7, an urethane foam cushion layer 8, and a base material 3 from the top. In the conventional skin constitution, most of the solar radiation energy passing through a window is converted into heat on the skin having low lightness. Part of the heat energy generated on the surface of the skin is transmitted to the air side by heat transfer, another part thereof is radiated as far infrared radiation, and the remainder is diffused by heat conduction to the inside thereof. At this time, the heat energy transmitted to the air and the heat energy radiated as the far infrared radiation become energy warming the vehicle's interior.

[0027] The heat energy conducted to the inside warms an inside of the part of the vehicle, and then is released indirectly to the vehicle's interior or released out of the vehicle through a body panel. Here, consideration is made on a distribution ratio of he heat energy released directly to the vehicle's interior and the heat energy conducted to the inside of the part. Since the current vehicle interior frequently uses resin with poor heat conduction, and moreover the heat insulating material such as urethane foam, there is no doubt that the heat energy released directly to the vehicle's interior is dominant. Accordingly, in the conventional skin structure, most of the solar radiation energy is instantly converted into heat causing an increase in temperature, which is supplied to the vehicle's interior.

[0028]FIG. 2 shows a representative example of a skin structure according to the present invention. In FIG. 2, the skin structure is composed of a light transmitting layer 6, a space holding layer 1, a low lightness layer 2, and a base material 3 from the top. FIG. 2 also shows a balance of the solar radiation energy. Most of the solar radiation energy having reached the light transmitting layer 6 is passed through the light transmitting layer 6, and then reaches the low lightness layer 2 or the base material 3, where the solar radiation energy is converted into heat for the first time. In the low lightness layer 2 or the base material 3, heat transfer and heat radiation to the air and heat conduction to the inside part occur similarly to the conventional skin. However, in this skin structure, since the portion generating heat is separated from the vehicle's interior by the light transmitting layer 6 and the space holding layer 1, there is no direct heat transfer into the air within the vehicle's interior. Generally, the resin is transparent for visible radiation and near infrared radiation, but is opaque for far infrared radiation, so that the far infrared radiation cannot be transmitted through the light transmitting layer 6. Accordingly, the far infrared radiation is not radiated directly into the vehlicle's interior. Actually, in the present invention, the bulk of solar radiation energy is stored within the skin structure.

[0029] Only by using the skin structure described above, the solar radiation energy directly released into the vehicle's interior is reduced, thus, easing the increase in temperature within the vehicle's interior. Furthermore, the improvement of the heat conduction of the base material makes it possible to dramatically suppress the heat released into the vehicle's interior.

[0030] The present invention solves the problems of the increase in surface temperature of the skin and its reflection by a window, both of which are antinomical in the conventional principle of reflection. Specifically, the color of the layer holding space or the underneath layer viewable therethrough is set to a low lightness color. The color of the appearance of the laminated material according to the present invention becomes the low lightness color viewable through the top surface layer. Therefore, the reflection by the window can be prevented.

[0031] As described above, a new laminated skin constitution was developed by adding several devices based on an entirely new principle of preventing an increase in surface temperature found by the inventors. Therefore, a skin structure having an innovative capability was realized, in which the temperature is not easily increased by direct solar radiation and the reflection by the window does not occur.

[0032] Next, effects of the present invention will be further described concretely for each component layer, including differences from the conventional art.

[0033]FIG. 3 shows an example of the skin structure according to the present invention. In FIG. 3, the skin structure is composed of the light transmitting layer 6, the space holding layer 1, the low lightness layer 2, and the base material 3 from the top.

[0034] The light transmitting layer 6 as the top surface layer of the present invention needs to be transparent to visible radiation and the near infrared radiation, which are principal components of sunbeams. In other words, the large difference between the skins of the present invention and the conventional art is the transparency of the top surface of the skin. In the conventional skin, a desired color tone is obtained by a white pigment such as titanium dioxide or zinc oxide, a black pigment such as carbon black, or various color pigments, and an extender such as calcium carbonate and talc is added thereto according to need. Accordingly, the conventional skin is completely opaque. On the contrary, in the present invention, the color tone of the skin is secured by the second layer or the layers below the second layer. Therefore, basically, it is preferable that pigments are not added to the top surface of the skin to secure the maximum transparency. However, this is not intended to prevent the addition of a small amount of color pigment or the addition of an extender for improving properties on request of design or the like. Certainly, additives such as an ultraviolet absorbent and a light stabilizer, which are not pigments, can be used freely similarly to the conventional materials.

[0035] Accordingly, in the top surface layer of the present invention, the presence of pigments or additives is not an essential difference, but a transmitting amount of light rays is an essential factor. Specifically, the light transmittance of the conventional skin is completely 0%. On the contrary, in the present invention, the skin having a light transmittance of at least 20% is visually transparent from the conventional wisdom, which is considered to be within the range of the present invention. However, from a thermal viewpoint, in a case where light transmittance is lower than 30%, much of incident light becomes heat on the surface and the effect of the present invention is significantly reduced. Therefore, the light transmittance is preferably 30% or more. In a case where the transmittance of light exceeds 98%, there is no thermal problem. However, if a certain sheet thickness is secured to obtain practical strength and durability, it is difficult to obtain light transmittance of 98% or more owing to absorption by the resin. Furthermore, in the case of taking measures to be described below for suppressing reflection on the top surface, practically it is difficult to secure transmittance of 98% or more.

[0036] The concept used as the light transmittance or the transmittance in the present invention is measured by a method described in the testing method on transmittance, reflectance and emittance of flat glasses and evaluation of solar heat gain coefficient defined in the Japan Industrial Standards R 3106 (ISO 9050). The light transmittance in the present invention is calculated by multiplying a light transmittance measured by means of spectrometry by a weighted coefficient given in the appendix table 2 of JIS R 3106 within a range of wavelength from 300 nm to 2500 nm.

[0037] If the top surface has excessively high luster, for example in a case where the sun is located at a low position, the light specularly reflected on the surface of the interior is too strong and interferes with the field of vision. Therefore, in the present invention, the light transmitting layer 6 preferably includes an anti-reflection function on the top surface thereof. Since the direct reflective property varies according to a shape of the interior, inequalities of the surface, or the like, the performance thereof cannot be completely specified only by reflectivity. However, the reflectivity is often determined to be about 30% or below for a 60-degree specular glossiness specified in the measurement method of specular glossiness of JIS Z 8741 (ISO 2813, ISO 7668) experientially. Accordingly, the reflectivity is desirably set within the above described range in the present invention. For reference, in the reflectivity of JIS Z 8741, the reflectivity of a surface of a black flat glass provided with a predetermined refractive index is defined to be 100%. Therefore, in the case where the reflectivity of a transparent film is measured by means of the above described method, since the reflection on the rear surface of the film is simultaneously measured, some measured values exceed 100%. Such an example will be later referred to in the examples, but is not an error measurement.

[0038] For anti reflection processing, there are several methods, and it is preferable that fine inequalities are formed on the surface from the perspective of design and mass production. As the method of forming the inequalities, a known embossing by means of a roll or mold transfer by means of slash molding is usually employed. Moreover, a lusterless paint having fine powder of silica dispersed therein or the like can be painted on the top surface. Furthermore, a method of changing the surface properties of the resin itself by adding a transparent flatting agent such as silica fine powder to the resin itself of the light transmitting layer 6 can be employed.

[0039] Simultaneously, the light transmitting layer 6 is required to possess strength, flexibility, light resistance, and the like, which are essential properties as a skin material. As the resin which is provided with such properties and preferred for the present invention, soft polyvinyl chloride resin, which is also frequently used in current interior materials for vehicles, is preferred. Particularly, transparent polyvinyl chloride resin is a material which is industrially easy to be used in terms of the properties and the price. Moreover, ethylene, propylene, and other olefin-derived thermoplastic olefin (TPO) resin, which has begun to be used as an alternative material to the soft polyvinyl chloride resin in recent years, are preferable for the same reason. Furthermore, polyurethane resin is excellent in flexibility and durability and frequently used as the skin material for vehicles. Accordingly, the polyurethane resin is also preferable for the present invention. However, this is not intended to prevent application of a transparent resin other than the resins cited above, and the other transparent resins can be properly used alone, or by copolymerization or mixing with the aforementioned resin.

[0040] Next, the requirement for a space holding layer 1 of the present invention is to provide insulation between the light transmitting layer 6 and the layer generating heat. Furthermore, the space holding layer 1 needs to secure transmission properties such that as many light rays as possible can reach the heat generation layer. In this sense, the essential requirements for the space holding layer 1 according to the present invention ale thickness and light transmittance.

[0041] Preferably, the thickness of the space holding layer 1 is 0.5 mm or more. With the thickness of less than 0.5 mm, the air layer as the insulation layer is excessively thin and the amount of heat retention thereof is small. Accordingly, heat transfer similar to contact heat transfer occurs, thus causing an early increase in surface temperature. On the other hand, the upper limit of the thickness is desirably 20 mm. The space holding layer 1 is surely preferred to be thicker in terms of heat, but a thickness of more than 20 mm inhibits the degree of freedom in dimensions of the parts. Accordingly, the skin structure becomes difficult to use practically as the skin.

[0042] Theoretically, the space holding layer 1 preferably has a higher light transmittance. However, in the case of using a fiber, which will be described later, preferably used in the present invention, the practical upper limit of the transmittance is about 95%. If transmittance exceeding the upper limit is secured, it becomes difficult to secure a desirable space with a thickness of 0.5 mm or more. However, this is not intended to prevent use of a raw material with an extremely high open area ratio, for example, a thin walled honeycomb member. On the other hand, from the viewpoint of heat exchange of the light rays at a position as far from the top layer as possible, in the case where particularly the space holding layer 1 is designed to be thick to a certain extent, so that even if the light rays are not transmitted to the rear surface of the air holding layer, the effect of the invention can be exerted. For example, the space holding layer 1 can employ a structure so that the light rays are absorbed in the vicinity of the bottom layer of the space holding layer 1 for heat exchange. However, as a structure for exerting the effect of the present invention while limiting the thickness to some extent as the skin, 5% or more of the light rays are desirably transmitted through the space (air) holding layer 1.

[0043] As the material of the space holding layer 1, the urethane foam material hitherto used in the cushion layer of the interior is not preferable from the viewpoint of light transmittance because of a closed cell structure thereof. A three-dimensional mesh structure or a fiber for allowing light rays to be transmitted is preferred. Here, examples of the three-dimensional mesh structure include a thin walled honeycomb member-, a structure having a section composed of circles similar to a honeycomb, and a polygonal member other than the honeycomb. As the fiber, woven fabric or non-woven fabric is employed. Taking the above described requirement into account, to secure thickness with fewer fibers, a woven fabric or non-woven fabric using fibers thicker than typical fibers for clothing is preferably used. Particularly in the recent years, three dimensional textiles have been brought into market as cushion members with air permeability. A three dimensional fabric meets the purpose of the present invention and is preferably used. As the three dimensional fabric, there is three dimensional nylon knitted fabric with a trade name “Fusion-1 series” marketed by ASAHI KASEI CORPORATION. The thickness, the cushion ability, the light transmittance, and the color tone thereof can be selected in accordance with the requirement. However, this is not intended to limit the types of fiber to a three dimensional knitted fabric, and it goes without saying that the fiber can be realized with non-woven fabric or typical tricot or raschel fabric in principle.

[0044] Since the space holding layer 1 is viewable from outside through the light transmitting layer 6 to some extent, the space holding layer 1 is required not to be an obstacle to reflection in the window. Although the degree of the reflection in the window depends on the projection area of the space holding layer 1, the color tone of the raw material and the surface reflection tend to be seen. Accordingly, the color tone thereof is preferably set to have low lightness. Particularly, in the case of setting the light transmittance of the space holding layer 1 to be low, the color tone of the space holding layer 1 plays a leading role in determination of the color tone of the top skin layer. Therefore, the color tone of the space holding layer 1 is preferably set to 6.0 or below by the Munsell value. Typically, the color tone of the surface of the interior, which assumes the reflection in the window, is often targeted with a maximum lightness of about 4.0. In the case where the Munsell value of the fiber of the present invention exceeds 6.0, even if the lightness is somewhat dropped in the transmitting layer or the low lightness layer, concealment thereof is difficult, and the degree of the reflection in the window becomes unignorable. On the other hand, the minimum lightness becomes 0 based on a definition of the lightness because it is preferred that the fiber is black in the present invention. Here, the color tone means the Munsell value. Specifically, the color tone is calculated by x, y, and a Y value obtained by a method of color measurement defined in JIS Z 8722 (method of object color measurement with 2-degree vision) (ISO 7724-1, ISO 7724-2).

[0045] Functions of the low lightness layer 2 in a thermal sense include absorption of the sunbeam and heat generation accompanied therewith. Moreover, the functions of the low lightness layer 2 include prevention of reflection in the window mentioned in the requirement for the space holding layer 1. From the above requirements, lower lightness is preferred. The minimum lightness is 0 of black, and the maximum lightness is about 6.0 as described above. With lightness of more than about 6.0, there is concern that reflection in the window may occur. However, for example in the case where the space holding layer 1 is designed to have a low lightness by lowering the light transmittance, since the color tone under the space holding layer 1 becomes difficult to observe, the low lightness layer 2 may be omitted, or a base material having a lightness of 6.0 or more may be used.

[0046] The materials for use in the low lightness layer 2 are not limited in the present invention. For example, in the case where the embodiment of the present invention is a laminated sheet of three layers, the low lightness layer 2 desirably employs a flexible sheet. Moreover, the low lightness layer 2 can employ a resin film, woven fabric, or non-woven fabric, which is colored to have low lightness. Alternatively, sheets may be used as the light transmitting layer 6 and the space holding layer 1, and the low lightness layer 2 may serve as a frame base material of the interior material. In such a case, the material of the heat generation layer can be fiber-reinforced resin pre-colored low lightness color, for example. Alternatively, for example in the case of using a metal such as aluminum or steel, after coloring the surface of the frame base material to have low lightness, a step of bonding the light transmitting layer 6 and the space holding layer 1 can be performed.

[0047] It is particularly advantageous for the present invention that the low lightness layer 2 is constituted by a conductive material or the conductive material is laminated in the low lightness layer 2. Specifically, the heat energy generated in the low lightness layer 2 and insulated by the space holding layer 1 is led to the rear side of the interior part, further out of the vehicle, thus providing an effect of reducing heat release into the vehicle. Concretely, it is extremely effective that one or a combination of metal powder, metallic fibers, a metallic net, a metal sheet, carbon powder, carbon fibers, ceramic powder, ceramic fibers, and a ceramic mat is contained or laminated in the low lightness layer as the highly heat conductive material.

[0048] The base material 3 can employ a known material such as a hard PVC plate and an aluminum plate. Preferably, the base material 3 contains a highly conductive material. The heat energy generated in the low lightness layer 2 or the base material 3 and insulated by the space holding layer 1 is led to the rear side of the interior part, or further out of the vehicle, thus providing an effect of further reducing heat release into the vehicle's interior. Concretely, it is extremely effective for one or a combination of metal powder, metallic fibers, a metallic net, a metal sheet, carbon powder, carbon fibers, ceramic powder, ceramic fibers, and a ceramic mat to be contained or laminated in the base material as the highly heat conductive material.

[0049] The skin structure of the present invention is obtained by attaching an adhesive agent between the layers of the light transmitting layer 6, the space holding layer 1, the low lightness layer 2, and the base material 3 and then performing a known method such as a hot press.

[0050]FIG. 4 shows a skin structure obtained by eliminating the light transmitting layer from the skin structure shown in FIG. 3. In FIG. 4, the space holding layer 1, the low lightness layer 2, and the base material 3 can employ the same materials used in FIG. 3. This skin structure does not include the light transmitting layer, but includes the space holding layer 1, low lightness layer 2, and base material 3. Accordingly, the above described transmission principle can be embodied, and the incident sunbeams can be transmitted to the low lightness layer 2 as the lower layer and the base material 3, thus preventing a direct increase in temperature of the surface layer. Furthermore, since the space holding layer 1 has high light transmittance, reflection in the window can be prevented.

[0051]FIG. 5 shows another example of the skin structure of the present invention. In FIG. 5, the skin structure is composed of a light transmitting layer 6, the space holding layer 1, and a low lightness base material 4 from the top. The light transmitting layer 6 and the space holding layer 1 can employ the same materials as the skin structure shown in FIG. 3.

[0052] Functions of the low lightness base material 4 in a thermal sense include absorption of the sunbeam and heat generation accompanied therewith. Moreover, the functions of the low lightness base material 4 include prevention of reflection in the window mentioned in the requirement for the space holding layer 1. From the above requirements, a lower lightness is preferred. The minimum lightness is 0 of black, and the maximum lightness is about 6.0 as described above. With lightness of more than about 6.0, there is a fear that the reflection in the window may occur. As specific examples of the low lightness base material 4, materials such as a hard PVC plate and an aluminum plate, which are colored to have low lightness, can be exemplified. However, for example in the case where the space holding layer 1 is designed to have a lower lightness by lowering the light transmittance thereof, since the color tone under the space holding layer 1 becomes difficult to observe, a base material having a lightness of 6.0 or more can be used.

[0053] The skin structure of the present invention is obtained by attaching an adhesive agent between the layers of the light transmitting layer 6, the space holding layer 1, and the low lightness base material 4 and then performing a known method such as hot press.

[0054]FIG. 6 shows a skin structure obtained by eliminating the light transmitting layer from the skin structure shown in FIG. 5. In FIG. 6, the space holding layer 1 and the low lightness base material 4 can employ the same materials as used in FIG. 5. This skin structure does not include the light transmitting layer. However, since the skin structure includes the space holding layer 1 and the low lightness base material 4, the above described transmission principle can be embodied. This skin structure allows the incident sunbeam to be transmitted to the low lightness base material 4 as the lower layer, thus preventing a direct increase in temperature of the surface layer. Furthermore, since the space holding layer 1 has high light transmittance, reflection in the window can be prevented.

[0055]FIG. 7 shows another example of the skin structure of the present invention. In FIG. 7, the skin structure is composed of the light transmitting layer 6, a low lightness space holding layer 5, and the base material 3 from the top. The light transmitting layer 6 and the base material 3 can employ the same materials as used in the skin structure shown in FIG. 3.

[0056] Functions of the low lightness space holding layer 5 in a thermal sense include absorption of the sunbeam and heat generation accompanied therewith. Moreover, the functions of the low lightness space holding layer 5 include prevention of reflection in the window mentioned in the requirement for the space holding layer. From the above requirements, a lower lightness is preferred. The minimum lightness is 0 of black, and the maximum lightness is about 6.0 as described above. With lightness of more than about 6.0, there is a fear that the reflection in the window may occur. In the case of using the low lightness space holding layer 5, since the color tone under the low lightness space holding layer 5 becomes difficult to observe, a base material having a lightness of 6.0 or more can be used.

[0057] As the material for use in the low lightness space holding layer 5, the above described three dimensional mesh structure or fiber colored to have low lightness can be employed.

[0058] The skin structure of the present invention is obtained by attaching an adhesive agent between the layers of the light transmitting layer 6, the low lightness space holding layer 5, and the base material 3 and then by a known method such as hot press.

[0059]FIG. 8 shows a skin structure obtained by eliminating the light transmitting layer from the skin structure shown in FIG. 7. In FIG. 8, the low lightness space holding layer 5 and base material 3 can employ the same materials used in FIG. 7. This skin structure does not include the light transmitting layer. However, since the skin structure includes the low lightness space holding layer 5 and the base material 3, the above described transmission principle can be embodied. Accordingly, the incident sunbeams can be transmitted to the base material 3 as the lower layer, thus preventing a direct increase in temperature of the surface layer. Furthermore, since the low lightness space holding layer 5 has light transmittance which is not excessively low, reflection in the window can be prevented.

[0060] Application of the skin structure of the present invention includes a case of preventing an increase in surface temperature of the interior part directly exposed to sunlight. In this sense, the skin structure can be used in general vehicles or typical interior products. Particularly in the vehicles, the thermal environment in the blazing sunshine is very bad, so that the effect of the present invention is marked. As shown in FIG. 9, among the interior parts, an instrument panel 30, a door trim 31, a rear parcel shelf 32, a pillar garnish 33, and the like are suitable for application of the present invention. The above parts are arranged in portions for directly receiving the solar radiation, and the above parts needs consideration of the reflection in the window. Particularly, with regard to the instrument panel 30, the area thereof is large, and the requirement for the prevention of the reflection in the window is essential. Therefore, the instrument panel is a part where the application of the present invention is most effective.

[0061] Next, description will be made for the present invention with examples more specifically. These examples are intended to explain the present invention, and the present invention is not limited by these examples.

EXAMPLE 1

[0062] A transparent polyvinyl chloride resin sheet (light transmittance: 89%, 60-degree specular glossiness: 115%) of 0.05 mmt was used as the light transmitting layer. A three dimensional knitted fabric (light transmittance: 35%, lightness: 0.2) of 5 mmt made by ASAHI KASEI CORPORATION with a trade name Fusion-I and a product number AKE69440 was used as the space holding layer. Black spunbond non-woven fabric (lightness: 0.5) of 0.25 mmt made by Toyobo Co., Ltd with a trade name HEIM H6501AD was used as the low lightness layer. A light gray hard vinyl chloride plate of 3.0 mmt was used as the base material. Hot-melt adhesive powder made by Sumitomo Chemical Co., Ltd. with a trade name Bond First B was attached between the layers, and then the above-mentioned materials were subjected to hot press under conditions of 120° C. for 5 minutes with a spacer of 3.5 mm interposed. According to the above mentioned steps, a laminate test piece of 300 mm×300 mm was obtained.

EXAMPLE 2

[0063] A transparent polyvinyl chloride resin sheet (light transmittance: 89%, 60-degree specular glossiness: 115%) of 0.05 mmt was used as the light transmitting layer. A three dimensional knitted fabric (light transmittance: 35%, lightness: 0.2) of 5 mmt made by ASAHI KASEI CORPORATION with a trade name fusion-I and a product number AKE69440 was used as the space holding layer. As the low lightness base material layer, a painted resin plate obtained by subjecting a hard vinyl chloride plate of 3.0 mmt to black lusterless painting with lightness of 0.1 by use of acrylic paint was used. Hot-melt adhesive powder made by Sumitomo Chemical Co., Ltd. with a trade name Bond First B was attached between the layers, and then the above-mentioned materials were subjected to hot press under conditions of 120° C. and 5 minutes with a spacer of 3.5 mm interposed. From the above mentioned steps, a laminate test piece of 300 mm×300 mm was obtained.

EXAMPLE 3

[0064] A transparent polyvinyl chloride resin sheet (light transmittance: 89%, 60-degree specular glossiness: 115%) of 0.05 mmt was used as the light transmitting layer. A fiber of non-woven fabric (light transmittance: 5%, lightness: 2.3) was used as the space holding layer. A hard vinyl chloride plate of 3.0 mmt was used as the base material. The fiber (basis weight: 250 g/m²) composed of black pre-colored polyester (PET) fibers (fiber diameter: 13 denier, fiber length: 51 mm) of 80% and PET conjugate fibers (fiber diameter: 3 denier, fiber length: 51 mm, core component: PET, sheath component: polyester copolymer with a melting point of 170° C.) of 20% was prepared by card and cross layer. The above described skin material was laminated thereon, heated at 210° C., and then pressure-formed by means of cold press, thus obtaining the fiber of non-woven fabric. The obtained fiber of non-woven fabric had a thickness of 10 mm. Hot-melt adhesive powder made by Sumitomo Chemical Co., Ltd. with a trade name Bond First B was attached between the layers, and then the above-mentioned materials were subjected to hot press under conditions of 120° C. for 5 minutes with a spacer of 3.5 mm interposed. From the above mentioned steps, a laminate test piece of 300 mm×300 mm was obtained.

EXAMPLE 4

[0065] Urethane lusterless clear paint containing silica fine powder was applied on the surface of a transparent polyvinyl chloride resin sheet (light transmittance: 62%, 60-degree specular glossiness: 18%) of 0.05 mmt, and then a leather-like pattern was embossed thereon by means of an embossing roll. A laminate test piece was obtained in the same manner as Example 1, by using the resultant sheet as the light transmitting layer.

EXAMPLE 5

[0066] A laminate test piece was obtained in the same manner as Example 1 by using a blue-colored polyvinyl chloride resin sheet (light transmittance: 40%, 60-degree specular glossiness: 82%) of 0.05 mmt as the light transmitting layer.

EXAMPLE 6

[0067] A laminate test piece was obtained in the same manner as Example 1 by using a blue-colored polyvinyl chloride resin sheet (light transmittance: 40%, 60-degree specular glossiness: 82%) of 0.05 mmt as the light transmitting layer, and three dimensional knitted fabric (light transmittance: 82%, lightness: 7.5) of 3 mmt made by ASAHI KASEI CORPORATION with a trade name Fusion-I and a product number AKE64606 as the space holding layer.

EXAMPLE 7

[0068] A laminate test piece was obtained in the same manner as Example 2 by using a black painted aluminum plate (lightness: 0.5) of 1.0 mmt as the low lightness base material layer.

CONVENTIONAL EXAMPLE

[0069] A black pigment-colored non-flat polyvinyl chloride resin sheet (light transmittance: 0%, 60-degree specular glossiness: 4.5%) of 0.15 mmt was used as the surface layer, the resin being for use in the skin of the instrument panel. An urethane foam sheet of 5.0 mmt was used as the cushion layer; and a light gray hard vinyl chloride plate of 3.0 mmt was used as the base material. Hot-melt adhesive powder made by Sumitomo Chemical Co., Ltd. with a trade name Bond First B was attached between the layers, and then the above-mentioned materials were subjected to hot press under conditions of 120° C. for 5 minutes with a spacer of 3.5 mm interposed. For the above mentioned steps, a laminate test piece of 300 mm×300 mm was obtained.

COMPARATIVE EXAMPLE 1

[0070] A transparent polyvinyl chloride resin sheet (light transmittance: 89%, 60-degree specular glossiness: 115%) of 0.05 mmt was used as the light transmitting layer. Black spunbond non-woven fabric (lightness: 0.5) of 0.25 mmt made by Toyobo Co., Ltd with a trade name HEIM H6501AD was used as the low lightness base material. A light gray hard vinyl chloride plate of 3.0 mmt was used as the base material. Hot-melt adhesive powder made by Sumitomo Chemical Co., Ltd. with a trade name Bond First B was attached between the layers, and then the above-mentioned materials were subjected to hot press under conditions of 120° C. for 5 minutes with a spacer of 3.5 mm interposed. For the above mentioned steps, a laminate test piece of 300 mm×300 mm was obtained.

[0071] (Performance Evaluation)

[0072] For the obtained laminate test piece, an artificial solar radiation test for evaluating a performance of preventing an increase in surface temperature and a sensory evaluation for evaluating the reflection in the window.

[0073] Moreover, in order to verify the effect in an actual vehicle, the skin of the vinyl chloride resin skin and the urethane foam layer in the upper portion of the instrument panel were actually removed, and then the test piece of Example 1 was attached on the exposed surface of the base material with a cold curing rubber adhesive. Comparative evaluation was made between the part thus obtained and a current part in an environmental testing room.

[0074] (Artificial Solar Radiation Test)

[0075]FIG. 10 is a schematic view for explaining the evaluation method of the artificial sunlight test. In FIG. 10, the structure of the instrument panel shown in FIG. 6 is simulated. In the structure of the above described simulation apparatus, a laminate member 14 cut into 300 mm×300 mm was placed in a wooden box 15 including a heat reservoir and a heat release hole 16. Furthermore, at a distance of about 100 mm from the laminate member 14, a green glass plate 12 (light transmittance: 60% based on JIS R 3106 (ISO 9050)) for automobile of 3.5 mmt, which imitates the window, was placed, and the increase in temperature within the vehicle was simulated.

[0076] On the surface of the laminate member 14, a thermocouple 13 was placed, thus making it possible to measure temperature change of the laminate member 14. With regard to heat load, a solar simulator (SERIC LTD.) 11 composed of four lamps of artificial sunlight with 500 W was placed over the laminate member 14 and adjusted such that the radiation energy becomes 1000 W/m² on the surface of the glass plate 12. The measurement was carried out in the room conditioned at 25° C. in 60 minutes after starting the radiation to the laminate member 14, that is, at the time when the increase in surface temperature of the laminate member 14 approximately came to equilibrium.

[0077] (Sensory Evaluation of Reflection in the Window)

[0078]FIG. 11 is a schematic view for explaining sensory evaluation of the reflection in the window.

[0079] In FIG. 11, a green glass plate 18 for an automobile window (light transmittance: 60% based on JIS R 3106 (ISO 9050)) of 3.5 mmt was placed above black flock paper 21 at 30° from the horizon. Furthermore, an unformed flat plate 19 (500 mm×500 mm) of the laminate sample was placed on the flock paper 21. Radiation was made by a 500 W lamp 17 of artificial sunlight from the height of about 2 m, and then the illuminance at the location of the sample is adjusted to 6000 lux. The degree of the reflection was evaluated by means of visual observation 20.

[0080] The significant level as compared with the conventional example is judged Y, the level where some reflection was observed but the degree thereof is very low and need not to be cared is judged C, and the level where the reflection was apparently large and interfered with the field of vision was judged N.

[0081] (Evaluation of In-Vehicle State)

[0082] The vehicle was placed in the environmental testing room including an infrared lamp and a fan/air conditioner, and the environment was set under the following conditions. After the vehicle was soaked for 60 minutes, the surface temperature of the instrument panel was measured by means of the thermocouple.

[0083] Solar radiation strength: 767 W/m²

[0084] Temperature: 35° C.

[0085] Humidity: 70% RH

[0086] Wind velocity: 0.8 m/sec

[0087] (Evaluation Result)

[0088] The results of the evaluation are shown in Table 1. TABLE 1 Sensory test of Artificial sunlight reflection in In-vehicle test (° C.) window evaluation (° C.) Example 1 61.3 Y 62.3 Example 2 59.8 Y — Example 3 65.3 Y — Example 4 66.0 Y — Example 5 70.8 Y — Example 6 68.4 C — Example 7 51.1 Y — Conventional 89.2 Y 93.6 example Comparative 85.9 Y — example 1

[0089] The entire content of a Japanese Patent Application No. P2002-7369 with a filing date of Jan. 16, 2002 is herein incorporated by reference.

[0090] Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above will occur to these skilled in the art, in light of the teachings. The scope of the invention is defined with reference to the following claims. 

What is claimed is:
 1. A skin structure, comprising: a base material; a low lightness layer laminated on the base material, the low lightness layer showing low lightness to incident light; and a space holding layer laminated on the low lightness layer, the space holding layer forming a space on the low lightness layer.
 2. A skin structure, comprising: a base material; and a space holding layer laminated on the base material, the space holding layer forming a space on the base material, wherein the base material is set to have low lightness.
 3. A skin structure, comprising: a base material; and a space holding layer laminated on the base material, the space holding layer forming a space on the base material, wherein the space holding layer is set to have low lightness.
 4. The skin structure of claim 1, further comprising: a light transmitting layer laminated on the space holding layer, the light transmitting layer allowing the incident light to be transmitted therein.
 5. The skin structure of claim 4, wherein a light transmittance of the light transmitting layer ranges from 30% to 98%.
 6. The skin structure of claim 1, wherein a thickness of the space holding layer ranges from 0.5 mm to 20 mm.
 7. The skin structure of claim 1, wherein a light transmittance of the space holding layer ranges from 5% to 95%.
 8. The skin structure of claim 1, wherein a Munsell value of the low lightness layer is 6.0 or below.
 9. The skin structure of claim 2, wherein a Munsell value of the base material is 6.0 or below.
 10. The skin structure of claim 4, wherein a surface of the light transmitting layer has an anti-reflection function.
 11. The skin structure of claim 1, wherein a Munsell value of the space holding layer is 6.0 or below.
 12. The skin structure of claim 1, wherein the space holding layer is a fiber.
 13. The skin structure of claim 1, wherein the space holding layer is three dimensional fabric.
 14. The skin structure of claim 4, wherein the light transmitting layer comprises at least one of resins selected from polyvinyl chloride resin, thermoplastic olefin resin, and polyurethane resin.
 15. The skin structure of claim 1, wherein the low lightness layer includes a highly heat conductive material.
 16. The skin structure of claim 1, wherein the base material includes a highly heat conductive material.
 17. An interior part, comprising: a skin structure comprising a base material; a low lightness layer laminated on the base material, the low lightness layer showing low lightness to incident light; and a splice holding layer laminated on the low lightness layer, the space holding layer forming a space on the low lightness layer.
 18. The interior part of claim 17, wherein the skin structure is applied to at least one of parts selected from an instrument panel, a door trim, a rear parcel shelf, and a pillar garnish of the interior parts. 